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ROBO_DONUT
Tux's lil' helper
Joined: 03 Jan 2005
Posts: 144
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 Posted: Wed Jul 20, 2005 9:36 pm Post subject: Putting existing Gentoo install on RAID-0 |
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| I just purchased a an 80GB ATA 133 8MB cache Maxtor hard drive, and I want to set up a RAID 0 configuration using this drive and the drive I am currently using, another 80GB ATA 133 8MB cache hard drive (seagate possibly?). I already have a PCI card for RAID because my motherboard has some broken IDE channels, its a belkin card, but I have no other information because there's no information this card anywhere. I actually had to completely remove the card just to install some distrobutions (Fedora and some other one) and it is not currently configured because there were no drives on it for a while. I would like to keep my current installation. What should I do? |
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BradN
Advocate
Joined: 19 Apr 2002
Posts: 2391
Location: Wisconsin (USA)
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| Posted: Wed Jul 20, 2005 11:49 pm Post subject: |
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I strongly recommend just using linux software RAID. I've been running a 3x160GB configuration in raid5 for about a year now with no problems, and once you get used to the mdadm commands, it's easy to set up. Unless your raid card offers true hardware support (even if it does, proceed with caution), I'd recommend staying away from it for built-in raid support (but if it's a software RAID card, you can probably find a driver in the linux kernel to use it as normal IDE channels if you're running out of them).
For performance reasons, it's usually good to only have one drive per cable.
Check out http://gentoo-wiki.com/HOWTO_Gentoo_Install_on_Software_RAID for some more info
Also, I don't believe you will be able to create a RAID0 setup while preserving data on the first drive - you'll need to borrow a friend's drive or backup the data to another computer/CD/DVD/whatever. If you were going to set up a RAID1 volume instead, you could keep the data by creating the RAID using the 2nd drive and a missing drive, copy data to it, and then add the first drive to the RAID volume.
good luck |
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ROBO_DONUT
Tux's lil' helper
Joined: 03 Jan 2005
Posts: 144
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| Posted: Thu Jul 21, 2005 8:56 am Post subject: |
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I have to install windows also, so I don't know if linux software raid is going to work. My other computer has about 10 GB free on the hard drive, which is more then the contents of my gentoo partition, so I shouldn't have a problem moving it to the other hard drive if I can find the proper software.
Edit: It took me a while, but I've found some documentation on the card. Pretty much the only useful info in it was that it's a software raid card.
card
chip |
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ROBO_DONUT
Tux's lil' helper
Joined: 03 Jan 2005
Posts: 144
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| Posted: Thu Jul 21, 2005 11:40 am Post subject: |
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| I really need help with this. |
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fw146
n00b
Joined: 29 Dec 2003
Posts: 42
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| Posted: Thu Jul 21, 2005 2:15 pm Post subject: |
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| ROBO_DONUT wrote: | | I really need help with this. |
I have Sil-0680 based card, which is supported. It may even be the same thing as 680A, not sure about it. Making sure that it is supported is the first step. As you already have gentoo on the machine, the best way to ensure that it works is to activate (as a module perhaps) | Code: | Device Drivers -->
ATA/ATAPI/MFM/RLL support --->
Silicon Image chipset support |
I would also recommend linux software RAID over "bios" software raid. In the past I have found that "bios" based software RAID-0 yielded absolutely no performance benefit, while the linux software RAID gave me 2x (roughly) performance gain. Of course the former could have been entirely my fault  .
The safe, easy and good (in my opinion) way to set this up under dual boot is to NOT have RAID-0 for windows. Consider the following scenerio: You want raid-0 for var and home. Then you could - Create 4 partitions on /dev/hde.
- /dev/hde1 30GB for windows C:.
- /dev/hde2 1 GB linux swap
- /dev/hde3 4 GB linux part of RAID-0 for var
- /dev/hde4 35 GB linux, part of RAID-0 for home
- Create 5 partitions on /dev/hdg
- /dev/hdg1 20 GB for windows D:
- /dev/hdg2 4GB linux root (/)
- /dev/hdg3 7GB linux usr
- /dev/hdg4 4 GB linux part of RAID-0 for var
- /dev/hdg5 35 GB linux, part of RAID-0 for home
I am sure you will take this as an example and not a recipe. To setup the actual software RAID part, please refer to The Software-RAID Howto. It is excellent and I could not possibly improve on it
EDIT: Another advantage of using software RAID is that you can have disks that are of different sizes. You just have to make sure that the partitions which form the RAID device are of equal size. |
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ROBO_DONUT
Tux's lil' helper
Joined: 03 Jan 2005
Posts: 144
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| Posted: Thu Jul 21, 2005 6:21 pm Post subject: |
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| Thanks for the help, but I really need the performance boost in windows, everything in my gentoo installation already runs fast enough. I use my windows partion for playing games and making maps in Hammer, this requires me to constantly load textures, maps, models, etc. Is it possible to get gentoo and windows on the same bios raid-0 drive? Am I going to have any problems, or is it just slower? |
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ForgotmyDew
n00b
Joined: 22 Apr 2003
Posts: 10
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| Posted: Thu Jul 21, 2005 6:59 pm Post subject: |
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| ROBO_DONUT wrote: | | Is it possible to get gentoo and windows on the same bios raid-0 drive? Am I going to have any problems, or is it just slower? |
That's a good question. Since BIOS raid on the Nforce and Intel ICH are just software raids, could you run Windows on nvraid and run Linux on mdraid? I'm more interested in RAID1, but it would go something like this:
nvraid for Windows with hda1+hdb1
mdraid for Gentoo with hda2+hdb2
I'm putting together an Nforce4 system right now, so I can afford to experiment and reformat if it doesn't work. |
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fw146
n00b
Joined: 29 Dec 2003
Posts: 42
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| Posted: Fri Jul 22, 2005 3:04 pm Post subject: |
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| ForgotmyDew wrote: | | ROBO_DONUT wrote: | | Is it possible to get gentoo and windows on the same bios raid-0 drive? Am I going to have any problems, or is it just slower? |
That's a good question. Since BIOS raid on the Nforce and Intel ICH are just software raids, could you run Windows on nvraid and run Linux on mdraid? I'm more interested in RAID1, but it would go something like this:
nvraid for Windows with hda1+hdb1
mdraid for Gentoo with hda2+hdb2
I'm putting together an Nforce4 system right now, so I can afford to experiment and reformat if it doesn't work. |
So here is the deal. The software RAID controllers I have used, "hide" the individual devices if you setup a RAID array. This is for obvious reasons. You would not want anything to write to the participating drives directly, possibly leading to data loss. How much data would be lost is of course dependent on the nature of the write operation.
For the Promise chips, kernel has an option of overriding the bios, allowing you to access the individual drives even if a RAID array has been created in the BIOS. So in this case, yes it is possible to have Windows access the array through bios and linux access it directly. Not sure about mdraid but you can use the device-mapper (the dm-???? modules). There is a tool called dmraid which attempts to read the metadata stored by the BIOS at the end of the drive and automate this process for you. I hope that I do not have to highlight the risks involved to you.
I have no equivalent information for your chip/controller/card. If the individual drives are not hidden from linux, then it will work. ROBO_DONUT, this means that if you can get it to work, you will probably not pay much performance penalty. FYI dmraid readme tells me that it supports silicon image medley as well as Nvidia nforce.
The bottomline is (pun intented) that you will have to try this for yourself to see how it works. |
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ForgotmyDew
n00b
Joined: 22 Apr 2003
Posts: 10
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| Posted: Sun Jul 24, 2005 7:25 pm Post subject: |
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| fw146 wrote: |
So here is the deal. The software RAID controllers I have used, "hide" the individual devices if you setup a RAID array. This is for obvious reasons. You would not want anything to write to the participating drives directly, possibly leading to data loss. How much data would be lost is of course dependent on the nature of the write operation.
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OK, I tried it myself, and here's what I found. On my Nforce4 board, I installed Windows XP on a RAID1 using the BIOS RAID. Then I booted up with a livecd and I could still see hda and hdb each with hda1 and hdb1 for NTFS. I combined hda and hdb in a mirror with dmsetup and it seemed to work. I could run fdisk on the mirror to partition it, but there were no device nodes for the partitions. The howto said I had to run dmsetup again to create devices for the partitions if I didn't use dmraid. That seemed pretty tedious and error-prone to me.
I think what I'll try next instead is partition the disks first and then mirror them with dmsetup. I know that won't work on a RAID0, but should be fine for RAID1. |
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